ST7LITE3xF2
INTERRUPTS (Cont’d)
EXTERNAL INTERRUPT CONTROL REGISTER
(EICR)
Read / Write
Reset Value: 0000 0000 (00h)
7
0
IS31 IS30 IS21 IS20 IS11 IS10 IS01 IS00
EXTERNAL INTERRUPT SELECTION REGIS-
TER (EISR)
Read / Write
Reset Value: 0000 0000 (00h)
7
0
ei31 ei30 ei21 ei20 ei11 ei10 ei01 ei00
Bit 7:6 = IS3[1:0] ei3 sensitivity
These bits define the interrupt sensitivity for ei3
(Port B0) according to Table 7.
Bit 5:4 = IS2[1:0] ei2 sensitivity
These bits define the interrupt sensitivity for ei2
(Port B3) according to Table 7.
Bit 3:2 = IS1[1:0] ei1 sensitivity
These bits define the interrupt sensitivity for ei1
(Port A7) according to Table 7.
Bit 1:0 = IS0[1:0] ei0 sensitivity
These bits define the interrupt sensitivity for ei0
(Port A0) according to Table 7.
Note: These 8 bits can be written only when the I
bit in the CC register is set.
Table 7. Interrupt Sensitivity Bits
ISx1 ISx0
00
01
10
11
.
External Interrupt Sensitivity
Falling edge & low level
Rising edge only
Falling edge only
Rising and falling edge
Bit 7:6 = ei3[1:0] ei3 pin selection
These bits are written by software. They select the
Port B I/O pin used for the ei3 external interrupt ac-
cording to the table below.
External Interrupt I/O pin selection
ei31
ei30
0
0
0
1
1
0
1
1
I/O Pin
No interrupt *
PB0
PB1
PB2
* Reset State
Bit 5:4 = ei2[1:0] ei2 pin selection
These bits are written by software. They select the
Port B I/O pin used for the ei2 external interrupt ac-
cording to the table below.
External Interrupt I/O pin selection
ei21
ei20
0
0
0
1
1
0
1
1
I/O Pin
No interrupt *
PB3
PB5
PB6
* Reset State
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